Group 12 metal aryl selenolates. Crystal and molecular structure of [2-(Et2NCH2)C6H4]2Se 2 and [2-(Me2NCH2)C6H 4Se]2M (M = Zn, Cd)

Article abstract of DOI:10.1016/j.jorganchem.2010.07.036

Diorganodiselenide [2-(Et₂NCH₂)C₆H ₄]₂Se₂ (1) was obtained by hydrolysis/oxidation of the corresponding [2-(Et₂NCH₂)C₆H ₄]SeLi derivative. The treatment of [2-(Et₂NCH ₂)C₆H₄]₂Se₂ with elemental sodium in THF resulted in [2-(Et₂NCH₂)C ₆H₄]SeNa (2). Reactions between alkali metal selenolates [2-(R₂NCH₂)C₆H₄]SeM′ (R = Me, Et; M′ = Li, Na) and MCl₂ (M = Zn, Cd) in a 2:1 molar ratio resulted in the [2-(R₂NCH₂)C₆H ₄Se]₂M species [R = Me, M = Zn (3), Cd (4); R = Et, M = Zn (5), Cd (6)]. The new compounds were characterized by multinuclear NMR ( ¹H, ¹³C, ⁷⁷Se, ¹¹³Cd) and mass spectrometry. The crystal and molecular structures of 1, 3 and 4 revealed monomeric species stabilized by N → Se (for 1) and N → M (for 3 and 4) intramolecular interactions.

Full text of DOI:10.1016/j.jorganchem.2010.07.036

Journal of Organometallic Chemistry 695 (2010) 2486e2492
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Group 12 metal aryl selenolates. Crystal and molecular structure of [2-(Et2NCH2)
C6H4]2Se2 and [2-(Me2NCH2)C6H4Se]2M (M ¼ Zn, Cd)
,
a
b
Alpar Pöllnitz a, Adina Rotar a, Anca Silvestru a , Cristian Silvestru , Monika Kulcsar
*
a Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, RO-400028 Cluj-Napoca, Romania
b Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-C.S.I.C., E-50009 Zaragoza, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Diorganodiselenide [2-(Et2NCH2)C6H4]2Se2 (1) was obtained by hydrolysis/oxidation of the corre-
sponding [2-(Et2NCH2)C6H4]SeLi derivative. The treatment of [2-(Et2NCH2)C6H4]2Se2 with elemental
sodium in THF resulted in [2-(Et2NCH2)C6H4]SeNa (2). Reactions between alkali metal selenolates [2-
(R2NCH2)C6H4]SeM0 (R ¼ Me, Et; M0 ¼ Li, Na) and MCl2 (M ¼ Zn, Cd) in a 2:1 molar ratio resulted in the [2-
(R2NCH2)C6H4Se]2M species [R ¼ Me, M ¼ Zn (3), Cd (4); R ¼ Et, M ¼ Zn (5), Cd (6)]. The new compounds
were characterized by multinuclear NMR (1H, 13C, 77Se, 113Cd) and mass spectrometry. The crystal and
molecular structures of 1, 3 and 4 revealed monomeric species stabilized by N / Se (for 1) and N / M
(for 3 and 4) intramolecular interactions.
Received 6 May 2010
Received in revised form
20 July 2010
Accepted 30 July 2010
Available online 7 August 2010
Dedicated to Professor Hans J. Breunig,
a remarkable scientist, a very good friend
and an exceptional mentor, on the occasion
of his 65th anniversary.
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
Diorganodiselenide
Group 12 metal selenolates
NMR studies
X-ray diffraction
1. Introduction
strategies were used in order to stablize monomeric species and to
avoid polymerization, i.e. (i) the use of organochalcogenolato
Organoselenium and -tellurium compounds containing an
intramolecular N / E (E ¼ Se, Te) interaction have attracted much
interest in the last two decades, mainly due to their increased
stability as monomeric species and their applications in biology,
asymmetric synthesis, catalysis or microelectronics [1e18]. The
presence of an organic group containing donor atoms capable for
intramolecular coordination favoured also the isolation of mono-
meric metal chalcogenolates [19e25]. Of special interest are Group
12 metal complexes which are considered to be good candidates as
single-source precursors for CVD processes [21e25]. In order to
obtain M/E thin films of good quality by such processes, compounds
with monomeric structure, thermal stability and high volatility are
required. Even medium sized organic groups were observed to
result in dimeric or polymeric [M(ER)2]n species (M ¼ Zn, Cd, Hg;
E ¼ S, Se, Te; R ¼ Ph, n-Bu, 4-CH3C6H4, 2,4,6-Me3C6H2) [22,25e32].
However, it was noted that such complexes decompose thermally
with formation of ME and ER2 species [21,22,33]. Different
ligands with bulky substituents, (ii) the increase of the coordination
number to the metal centre by additional neutral ligands [22,28], or
(iii) combination of the advantages of both the above approaches by
using organic groups containing donor atoms capable for intra-
molecular coordination [21e25]. While bulky substituents in many
cases
generate
compounds
which
eliminate
dio-
rganodichalcogenides, thus resulting in elemental metal, and
dissociation of neutral ligands before the sublimation temperature
was observed, the last method seems to be a more attractive way to
increase the thermal stability and to prevent polymerization.
We have reported recently on the synthesis, solution behaviour
and molecular structures of various hypervalent organoselenium
compounds containing organic groups with pendant arms, i.e. 2-
(Me2NCH2)C6H4 [34] or 2-{X(CH2CH2)2NCH2}C6H4 (X ¼ O, NMe)
[35,36]. As a continuation of our previous studies on organo-
selenium compounds we report here on the synthesis and struc-
tural characterization, both in solution and solid state, of the new
hypervalent diorganodiselenide [2-(Et2NCH2)C6H4]2Se2 as well as
the new Group 12 metal complexes, [2-(R2NCH2)C6H4Se]2M
(R ¼ Me, Et; M ¼ Zn, Cd).
* Corresponding author. Tel.: þ40 264 193833; fax: þ40 64 190818.
E-mail address: ancas@chem.ubbcluj.ro (A. Silvestru).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.07.036

A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
2487
CH2NEt2 group, with singlet resonance for the CH2NEt2 protons and
equivalent ethyl groups attached to nitrogen.
The 1H NMR spectrum of complex 3 in CDCl3 solution suggests
the coordination of the nitrogen atom even at room temperature.
The CH2 protons and the methyl groups gave an AB spin system
with dA 3.14 and dB 4.06 ppm and two singlet resonances at
d 1.65
and 2.54 ppm, respectively. In case of the cadmium(II) complexes 4
and 6 and the zinc(II) complex 5 broad resonances were observed at
25 ꢁC, thus suggesting a fast dynamic process in solution.
For complex [{2-(Me2NCH2)C6H4}Se]2Cd (4) the 113Cd NMR
spectrum exhibits one resonance at
d
ꢀ196.2 ppm, consistent with
the presence of only one species in solution. For this compound
a variable temperature 1H NMR experiment was performed in CDCl3
solution. At 213 K a spectrum corresponding to the frozen structure
was obtained, showing an AB spin system for the methylene protons
Scheme 1.
(
dA 2.88 and dB 4.22 ppm) and two singlet resonances (
2.56 ppm) for the methyl protons. For both types of protons coales-
cence was achieved at 268 K and a free enthalpy
G# of 54.5 kJ molꢀ1
d 1.25 and
2. Results and discussion
D
2.1. Preparation and spectroscopic characterization
was calculated for the corresponding dynamic processes.
For compound 3 the temperature of coalescence was 328 K in
C6D6 and the calculated medium free enthalpy was
The new diorganodichalcogenide [2-(Et2NCH2)C6H4]2Se2 (1) was
obtained using the ortho-lithiation route. The organolithium reagent
[2-(Et2NCH2)C6H4]Li was prepared as a white solid by direct lith-
iation of the corresponding 2-(N,N-diethylaminomethyl)benzene
bromide with n-BuLi, in anhydrous hexane. The treatment of a THF
solution of [2-(Et2NCH2)C6H4]Li with finely grounded selenium
powder, under argon, followed by hydrolysis and air oxidation,
resulted in isolation of [2-(Et2NCH2)C6H4]2Se2 (Scheme 1).
Reaction of the appropriate alkali metal aryl selenolate
[{2-(R2NCH2)C6H4}Se]M0 (M0 ¼ Li, Na) with ZnCl2 or CdCl2, respec-
tively, in a 2:1 molar ratio, afforded isolation of [{2-(R2NCH2)C6H4}
Se]2M (R ¼ Me, Et, M ¼ Zn, Cd) (Scheme 2). The lithium 2-(N,N-dime-
thylaminomethyl)selenolate was obtained as previously described
[37]. The sodium 2-(N,N-diethylaminomethyl)selenolate (2) was
prepared by reacting [2-(Et2NCH2)C6H4]2Se2 with sodium, in anhy-
drous THF, and was isolated as a colorless, solid powder, extremely
sensitive to moisture.
D
G#
66.2 kJ molꢀ1 (66.1 for the CH2 protons and 66.3 kJ molꢀ1 for the
CH3 groups, respectively). For the ethyl substituted derivatives 5
and 6 free enthalpies of 56.7 and 55.1 kJ molꢀ1 were calculated at
268 K, respectively, for the dynamic process in which the CH2N
protons are involved. At low temperature the aliphatic region cor-
responding to the ethyl groups becomes very complex, due to their
non-equivalence and the protoneproton couplings.
The 77Se NMR spectra are consistent with the formation of the
metal complexes, the corresponding resonances (
d
e81.2 for 3, ꢀ111.5
for 4, ꢀ59.0 for 5 and ꢀ95.0 ppm for 6) being strongly upfield shifted
with respect to the resonances observed for [2-(Me2NCH2)C6H4]2Se2
(d
430 ppm [37]) or 1 (d 427.4 ppm).
The EI mass spectra for compounds 3 and 4 show peaks corre-
sponding to the molecular ion [m/z 492 for 3 (97%) and 542 for 4
(29%)] as well as fragments of lower mass, e.g. [2-(Me2NCH2)C6H4SeMþ]
[m/z 278 for 3 (23%) and 326 for 4 (8%)], [2-(Me2NCH2)C6H4SeþHþ]
[m/z 214 (68% for 3 and 100% for 4)] and [2-(Me2NCH2)C6H4]þ [m/z
134 (100% for 3 and 34% for 4)]. The ESI mass spectra for all four
complexes, in addition to the molecular ion and [2-(R2NCH2)
C6H4]2Se2]þ species, exhibit also ions with mass exceeding that
of the corresponding monomer, i.e. m/z 770 [{2-(Me2NCH2)
C6H4}3Se3Znþ2 ], m/z 866 [{2-(Me2NCH2)C6H4}3Se3Cdþ2 ], m/z 853
[{2-(Et2NCH2)C6H4}3Se3Znþ2 ]andm/z948 [{2-(Et2NCH2)C6H4}3Se3Cdþ2 ],
thus suggesting that in vapor phase dinuclear species are also
present. This behavior suggests that thermal decomposition occurs
by releasing the corresponding diorganodiselenide.
The compounds were isolated as yellow (1 and 6), pale yellow
(3) or colorless (4 and 5) solids and were recrystallized from
a CH2Cl2/n-hexane mixture. Elemental analyses and NMR data are
consistent with the anticipated formulations.
At low pressure (10ꢀ3 atm) the methyl substituted complex 3
sublime without decomposition at 162 ꢁC.
2.2. Spectroscopy
The NMR (1H, 13C) spectra, recorded in CDCl3 solution, at room
temperature, for compound 1 provided no evidence for the pres-
ence of N / Se intramolecular interactions in solution. The reso-
nance for the methylene protons of the pendant CH2NEt2 arm
2.3. Crystal and molecular structure of [2-(Et2NCH2)C6H4]2Se2 (1)
Single crystals of the diselenide 1 suitable for X-ray diffraction
studies were obtained from a CH2Cl2/n-hexane mixture (1/5, v/v).
The crystal contains discrete molecules. Selected interatomic
distances and angles are listed in Table 1, while the ORTEP-like
diagram is depicted in Fig. 1.
appears as singlet at
to nitrogen show the expected resonances, i.e. a quartet at
d
3.72 ppm. The ethyl organic groups attached
2.61
d
and a triplet at
d 1.06 ppm.
In the case of the sodium aryl selenolate 2 the 1H NMR spectrum
in THF-d8 solution revealed a similar behavior for the pendant
Intramolecular seleniumenitrogen interactions of significant
strength are established in the diorganodiselenide 1, i.e. N1/Se1
ꢀ
ꢀ
2.713(5) and N2/Se2 3.068(6) A (cf. SrvdW (Se,N) 3.54 A [38]), of
similar magnitude with those observed in other related deriva-
ꢀ
tives, e.g. [2-(Me2NCH2)C6H4]2Se2 [2.856(3)/2.863(4) A] [37], [2-{O
ꢀ
(CH2CH2)2NCH2}C6H4]2Se2
[2.813(2)/2.825(3) A],
[2-{MeN
ꢀ
(CH2CH2)2NCH2}C6H4]2Se2 [3.135(3)/2.7393(3) A] [36], bis[2-(4,4-
dimethyl-2-oxazolinyl)phenyl] diselenide [2.819(5)/2.705(5) A]
ꢀ
[39]. Due to the intramolecular N / Se interactions a distorted T-
Scheme 2.
shaped geometry is achieved around each selenium atom.

2488
A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
Table 1
ꢁ
ꢀ
Selected interatomic distances (A) and angles ( ) in compounds [2-(Et2NCH2)C6H4]2Se2 (1), [2-(Me2NCH2)C6H4Se]2Zn (3) and [2-(Me2NCH2)C6H4Se]2Cd (4).
1
3
4a
4b
N1eSe1
N2eSe2
Se1eSe2
2.713(5)
3.068(6)
2.3544(11)
Zn1eSe1
2.390(2)
2.124(5)
Cd1eSe1
Cd1eSe2
Cd1eN1
Cd1eN2
Se1eCd1eSe2
N1eCd1eN2
N1eCd1eSe1
N2eCd1eSe1
N1eCd1eSe2
N2eCd1eSe2
C1eSe1eCd1
C10eSe2eCd1
C9eN1eC8
2.534(1)
2.546(1)
2.397(8)
2.360(7)
142.01(5)
110.7(3)
94.5(2)
106.97(2)
107.97(2)
93.5(2)
Cd2eSe3
Cd2eSe4
Cd2eN3
Cd2eN4
2.519(1)
2.517(1)
2.400(8)
2.362(9)
141.5(5)
108.1(5)
94.2(2)
108.1(2)
107.2(2)
95.4(2)
Zn1eN1
N2eSe2eSe1
Se2eSe1eN1
N2eSe2eC12
C12eSe2eSe1
C1eSe1eN1
C1eSe1eSe2
C10eN1eC7
C10eN1eC8
C7eN1eC8
C7eN1eSe1
C8eN1eSe1
C10eN1eSe1
C18eN2eC21
C18eN2eC19
C21eN2eC19
C18eN2eSe2
C19eN2eSe2
C21eN2eSe2
174.6(1)
169.5(1)
71.5(2)
103.3(2)
74.9(2)
100.8(2)
110.7(5)
114.9(6)
112.2(5)
89.9(3)
108.6(3)
117.9(4)
112.5(7)
111.3(7)
110.5(7)
78.4(4)
Se1eZn1eSe10
N1eZn1eN10
N1eZn1eSe1
N10eZn1eSe1
C1eSe1eZn1
C9eN1eC8
C9eN1eC7
C8eN1eC7
C9eN1eZn1
C8eN1eZn1
C7eN1eZn1
131.45(8)
119.8(3)
101.0(2)
102.8(2)
98.8(2)
108.8(5)
109.6(5)
107.4(5)
109.8(4)
110.3(4)
110.9(3)
Se3eCd2eSe4
N3eCd2eN4
N3eCd2eSe3
N4eCd2eSe3
N3eCd2eSe4
N4eCd2eSe4
C19eSe3eCd2
C28eSe4eCd2
C27eN3eC25
C27eN3eC26
C25eN3eC26
C27eN3eCd2
C25eN3eCd2
C26eN3eCd2
C34eN4eC35
C34eN4eC36
C35eN4eC36
C34eN4eCd2
C35eN4eCd2
C36eN4eCd2
89.9(3)
88.5(3)
91.2(3)
88.0(4)
109.3(9)
111.6(8)
108.7(8)
114.9(6)
104.6(7)
107.5(6)
108.5(7)
108.5(8)
108.8(7)
106.2(6)
115.7(5)
108.9(5)
108.1(8)
106.7(8)
110.1(8)
106.6(7)
107.9(5)
117.1(6)
109.9(9)
109.3(9)
108.5(10)
107.6(8)
115.0(6)
106.4(7)
C9eN1eC7
C8eN1eC7
C9eN1eCd1
C8eN1eCd1
C7eN1eCd1
C17eN2eC18
C17eN2eC16
C18eN2eC16
C17eN2eCd1
C18eN2eCd1
C16eN2eCd1
124.3(5)
115.5(5)
ꢀ
The intramolecular N / Se coordination results in five-
membered SeC3N rings, folded along the imaginary Se/Cmethylene
axis, with nitrogens displaced out of the best SeC3 planes. This
induces planar chirality, with nitrogen as pilot atom and the
aromatic ring as chiral plane, similarly to the situation described for
other related diselenides [36e38]. As a consequence the compound
2.534(1)/Cd1eSe2 2.546(1) A in 4a and Cd2eSe3 2.519(1)/Cd2eSe4
ꢀ
2.517(1) A in 4b] and secondary by the nitrogen of the pendant arms.
The crystal of complex 3 consists of centrosymmetric discrete
molecules separated by normal van der Waals distances. Due to the
ꢀ
strong intramolecular N / Zn coordination [Zn1eN1 2.124(5) A; cf.
ꢀ
SrvdW(N,Zn) 2.94 A] [38], a distorted tetrahedral geometry is ach-
crystallizes as a racemate, i.e. 1:1 mixtures of (RN1,SN2) and (SN1,RN2
)
ieved around the metal centre, with a dihedral angle of 73.1ꢁ
between Zn1Se1N1 and Zn1Se10N10 planes. The two ZnSeC3N
metallacycles have boat conformations with selenium and Cmethy-
isomers, with respect to the two chelate rings in a molecular unit.
atoms in apices. The intramolecular N / Zn coordination
induces planar chirality. Compound 3 crystallizes in the chiral space
group P2(1)2(1)2(1) (orthorhombic) and therefore the investigated
lene
2.4. Crystal and molecular structure of [2-(Me2NCH2)C6H4]2M
[M ¼ Zn (3), Cd (4)]
0
crystal contains only the (RN1,RN1 ) isomer.
Single crystals of the complexes 3 and 4 suitable for X-ray
diffraction studies were obtained from a CH2Cl2/n-hexane mixture
(1/5, v/v). Relevant interatomic distances and angles are listed in
Table 1, while the ORTEP-like diagrams are depicted in Figs. 2 and 3,
respectively. For the cadmium derivative two independent mole-
cules are present in the unit cell.
In both compounds the organoselenolato groups behave as
monometallic biconnective moieties, being attached to the metal
centre covalently by selenium [Zn1eSe1 2.390(2) Å in 3; Cd1eSe1
The molecules of the cadmium complex 4 are similar to those of
the Zn analogue 3 with respect to the tetrahedral environment of
the metal centre. In both independent molecules the two six-
membered metallacycles formed per metal atom due to strong
intramolecular N / Cd coordination [Cd1eN1 2.397(8)/Cd1eN2
ꢀ
ꢀ
2.360(7) A in 4a, and Cd2eN3 2.400(8)/Cd2eN4 2.362(9) A in 4b;
ꢀ
cf. SrvdW(N,Cd) 3.14 A] [38] exhibit again twisted boat conforma-
tions with selenium and the Cmethylene atoms in apices. For the
resulted CdSe2N2 cores the dihedral angles between the planes
Cd1N1Se1/Cd1N2Se2 and Cd2N3Se3/Cd2N4Se4 are 79.1ꢁ for 4a
and 81.3ꢁ for 4b, respectively.
Fig. 2. ORTEP-like representation at 30% probability and atom numbering scheme for
isomer RN-3 [symmetry equivalent position (1 ꢀ x, 1 ꢀ y, z) is given by “prime”;
hydrogen atoms are omitted for clarity].
Fig. 1. ORTEP-like representation at 30% probability and atom numbering scheme for
isomer [RN1,SN2] ꢀ 1 (hydrogen atoms are omitted for clarity).

A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
2489
(R ¼ Me, Et; M ¼ Zn, Cd) were prepared and structurally charac-
terized. [2-(Et2NCH2)C6H4]2Se2 diorganodiselenide exhibits
a similar structure in solution and in solid state as found for related
diorganodiselenides with nitrogen-containing pendant arm aryl
groups. The group 12 metal selenolates have monomeric structures
in solid-state, stabilized by intramolecular N / M interactions. The
mass spectra suggest the release of diorganodiselenide by thermal
decomposition in case of all four metal complexes.
4. Experimental
4.1. Materials and procedures
Starting materials were commercially available: selenium
powder, butyllithium (1.6 M in hexane), 2-bromobenzyl bromide,
ZnCl2, CdCl2 (Fluka) or prepared according to literature methods
([2-(Me2NCH2)C6H4]SeLi [37]). ZnCl2 and CdCl2 were dehydrated
before using. All manipulations were carried out under argon using
Schlenk techniques. Solvents were dried and distilled prior to use.
Elemental analyses were performed on a VarioEL analyzer. Melting
points were measured on an Electrothermal 9200 apparatus and
are not corrected. Multinuclear NMR spectra were recorded in dry
CDCl3, C6D6, CD2Cl2 or THF-d8 on a BRUKER AVANCE 300 instru-
ment operating at 300.1, 75.5 and 57.26 MHz for 1H, 13C and 77Se,
respectively, or a Bruker 500 machine operating at 500 and
111 MHz for 1H and 113Cd, respectively. The chemical shifts are
reported in ppm relative to the residual peak of solvent (ref. CHCl3:
1H 7.26, 13C 77.0 ppm; THF-d8: 1H 1.73 and 3.58, 13C 25.4 and
67.6 ppm, CD2Cl2: 1H 5.24 ppm, C6D6: 1H 7.15 ppm). 1H and 13C
resonances were assigned using 2D NMR experiments (COSY,
HMQC and HMBC). The 77Se spectra were obtained using diphenyl
diselenide as external standard. Chemical shifts are reported rela-
Fig. 3. ORTEP-like representation at 30% probability and atom numbering scheme for
isomer SN1,SN2e4a (hydrogen atoms are omitted for clarity).
Due to the planar chirality induced by the intramolecular
N / Cd coordination the compound crystallizes as a 1:1 mixture of
(RN1,RN2)/(SN1,SN2)e4a and (RN3,RN4)/(SN3,SN4)e4b isomers.
The main difference in the molecular structure of the two deriv-
atives consists in the orientation of the aromatic rings in the molec-
ular unit with respect to the best plane described by the nitrogen and
the methylene carbon atoms. In the zinc(II) complex 3 the two C6H4
ringsareplacedonthesamesideoftheN2C2 planeasaretheselenium
and the metal atoms, so that any intramolecular CeHmethyl/p
(Phcentroid) contact is prevented (Scheme 3a). By contrast, in the
cadmium(II) complex 4 the aromatic rings are placed on opposite side
of the N2C2 plane with respect to the selenium and the metal atoms
(Scheme 3b). This brings the aromatic rings closer to the methyl
groups attached to nitrogen and weak CeHmethyl/p (Phcentroid)
tive to dimethyl selenide (d 0 ppm) by assuming that the resonance
ꢀ
contacts are established [C9eH9B/Phcentroid(C10eC15) 2.85 A and
of the standard is at 461 ppm [40]. Mass spectra were recorded on
d
ꢀ
C18eH18C/Phcentroid(C1eC6) 3.03 A for 4a; C26eH26A/
a FINNIGAN MAT 8200 spectrometer (EI) or an Agilent 6320 Ion
Trap instrument (ESI).
ꢀ
Phcentroid(C28eC33) 2.87 A and C35eH35B/Phcentroid(C19eC24)
ꢀ
3.01 A for 4b].
Additional intermolecular CeHmethyl/p (Phcentroid) contacts
result in a layer arrangement in the crystal of 3, each molecule being
connected to other four neighboring molecules [C9eH9A/Phcentroid
3.04 A]. Chain polymers of alternating (SN1,SN2)e4a/(RN3,RN4)e4b
4.2. Synthesis of [2-(Et2NCH2)C6H4]2Se2 (1)
A solution of nBuLi in hexane (1.6 M, 27 mL) was added dropwise
ꢀ
and (RN1,RN2)e4a/(SN3,SN4)e4b molecules, respectively, can be
to
a stirred solution of 2-(N,N-diethylaminomethyl)benzene
considered in the crystal of the cadmium complex, for each molecule
bromide (10.483 g, 43.29 mmol) in 150 mL anhydrous hexane, at
room temperature. The reaction mixture was stirred at room
temperature for 24 h, when a white slurry of the lithiated product
was obtained. The white precipitate was separated by filtration and
washed with 3 ꢂ 30 mL hexane, yielding 2.38 g (30.6%) of the
lithiated derivative. The solid product (2.38 g, 14.06 mmol) was
disolved in 100 mL THF and selenium powder (1.11 g, 14.05 mmol)
was added. The reaction mixture was stirred for 2 h at room
temperature. The resulting yellowish solution was poured into
a beaker containing water (100 mL) and left overnight in an
ꢀ
only one aromatic ring being involved [C18eH18B/Phcentroid 2.97 A
ꢀ
and C26eH26B/Phcentroid 3.06 A]. No further interactions are
present between the parallel chains (see also Supplementary
material).
3. Conclusions
The new diorganodichalcogenide [2-(Et2NCH2)C6H4]2Se2, as
well as group 12 metal selenolates of type [2-(R2NCH2)C6H4Se]2M
Scheme 3.

2490
A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
Table 2
X-ray crystal data and structure refinement for compounds [2-(Et2NCH2)C6H4]2Se2 (1), [2-(Me2NCH2)C6H4Se]2Zn (3) and [2-(Me2NCH2)C6H4Se]2Cd (4).
1
C
3
4
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
22H32N2Se2
C18H24N2Se2Zn
491.68
297(2)
0.71073
Orthorhombic
P2(1)2(1)2(1)
C18H24CdN2Se2
538.71
297(2)
0.71073
Monoclinic
P2(1)/c
482.42
297(2)
0.71073
Monoclinic
P2(1)/c
ꢀ
Unit cell dimensions
ꢀ
a (A)
8.626(3)
9.632(3)
27.802(9)
90
98.457(7)
90
2284.7(12)
4
1.402
10.262(13)
14.613(19)
6.559(8)
90
90
90
984(2)
2
10.980(2)
9.402(2)
38.481(8)
90
90.890(4)
90
3972.1(15)
8
1.802
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
3
ꢀ
Volume (A )
Z
Dc (g/cm3)
1.660
4.950
488
Absorption coefficient (mmꢀ1
F(000)
)
3.245
984
4.765
2096
Crystal size, mm
q
0.31 ꢂ 0.30 ꢂ 0.27
2.24e25.00
10,683
3999 [R(int) ¼ 0.0553]
Full-matrix least-squares on F2
3999/0/239
1.143
R1 ¼ 0.0719,
wR2 ¼ 0.1289
R1 ¼ 0.1024,
wR2 ¼ 0.1394
0.537 and ꢀ0.537
0.40 ꢂ 0.37 ꢂ 0.30
2.43e25.00
4960
1740 [R(int) ¼ 0.0451]
0.48 ꢂ 0.37 ꢂ 0.28
2.12e25.00
27,874
6985 [R(int) ¼ 0.0726]
range for data collections (ꢁ)
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
1740/0/107
1.050
6985/0/423
1.187
Goodness-of-fit on F2
Final R indices [F2 > 2
s
(F2)]
R1 ¼ 0.0436,
wR2 ¼ 0.0835
R1 ¼ 0.0537,
wR2 ¼ 0.0872
0.373 and -0.494
R1 ¼ 0.0777,
wR2 ¼ 0.1375
R1 ¼ 0.1068,
wR2 ¼ 0.1477
1.002 and -1.239
R indices (all data)
ꢀꢀ3
Largest diff. peak and hole, eA
efficient fume hood for a complete oxidation. The organic phase
was separated and the aqueous phase was extracted several times
with methylene chloride. The combined organic phases were dried
over anhydrous MgSO4. Evaporation of the solvent gave 2 g (59%) of
the title compound as a pale yellow solid. M.p. 55 ꢁC. Anal. Found: C
54.83; H 6.82, N 6.11%. Calc. for C22H32N2Se2 (M ¼ 482.43): C 54.77,
anhydrous THF and the reaction mixture was stirred for 1 h at room
temperature. All selenium powder was dissolved during this
period. The resulted lithium selenolate solution was added drop-
wise under stirring to a cooled solution (ꢀ78 ꢁC) of ZnCl2 (0.33 g,
2.42 mmol) in 20 mL THF. The reaction mixture was left to reach
room temperature and stirred overnight. The solvent was removed
in vacuum and then the resulting solid was extracted with CH2Cl2.
LiCl was filtered off and the clear solution was concentrated to
approximately 2 mL. After treating with n-hexane 0.84 g (70.6%) of
the title compound was isolated as a pale yellow solid. M.p. 209 ꢁC.
Anal. Found: C 43.73, H 4.81, N 5.98. Calc. for C18H24N2Se2Zn
(M ¼ 491.70): C 43.97, H 4.92, N 5.70%. 1H NMR (CDCl3, 300 MHz,
H 6.69, N 5.81%. 1H (CDCl3, 300 MHz):
d
1.06 t (12H, NCH2CH3, 3JHH
3
7.1 Hz), 2.61q (8H, NCH2CH3, JHH 7.1 Hz), 3.72s (4H, CH2N), 7.13 m
3
4
(6H, C6H4, H3e5), 7.80dd (2H, C6H4, H6, JHH 6.8, JHH 2.1 Hz). 13C
(CDCl3, 75.5 MHz): 10.87 (NCH2CH3), 45.2 (NCH2CH3), 59.05
(CH2N), 125.57 (C5), 127.83 (C4), 128.35 (C3), 131.17 (C6), 133.74 (C2),
139.84 (C1). 77Se (CDCl3, 57.26 MHz):
427.4.
d
d
298 K):
d 1.67s (6H, NCH3), 2.55s (6H, NCH3), AB spin system with dA
2
3
3.14 and dB 4.07 (4H, CH2N, JHH 11.2 Hz), 6.97d (2H, C6H4, H4, JHH
4.3. Synthesis of [2-(Et2NCH2)C6H4]SeNa (2)
3
3
7.3 Hz), 7.03 t (2H, C6H4, H5, JHH 7.3 Hz), 7.05 t (2H, C6H4, H3, JHH
3
7.5 Hz), 7.8d (2H, C6H4, H6, JHH 7.3 Hz). 1H NMR (C6D6, 500 MHz,
[2-(Et2NCH2)C6H4]2Se2 (4 g, 8.29 mmol) was dissolved in
100 mL anhydrous THF under argon atmosphere. The THF solution
was added to a sodium mirror previously obtained in a round
bottom flask and left to react under stirring, at room temperature,
overnight. The resulting red clear solution was filtered off from
sodium and the solvent was evaporated at reduced pressure. The
obtained white solid was washed twice with hexane (2 ꢂ 10 mL) to
298 K):
d 1.03s (6H, NCH3), 2.22s (6H, NCH3), AB spin system with dA
2.50 and dB 3.89 (4H, CH2N, 2JHH 11.2 Hz), 6.54d (2H, C6H4, H4, 3JHH
3
3
7.2 Hz), 6.82 t (2H, C6H4, H5, JHH 7.2 Hz), 6.87 t (2H, C6H4, H3, JHH
7.4 Hz), 7.98d (2H, C6H4, H6, JHH 7.4 Hz). 1H NMR (C6D6, 500 MHz,
3
328 K): d 1.69s,br (12H, NCH3), 3.20s,br (4H, CH2N), 6.59d (2H, C6H4,
3
3
H4, JHH 7.3 Hz), 6.82 t (2H, C6H4, H5, JHH 7.2 Hz), 6.88 t (2H, C6H4,
3
3
H3, JHH 7.5 Hz), 7.94d (2H, C6H4, H6, JHH 7.5 Hz). 13C NMR (CDCl3,
remove all unreacted diselenide and dried in vacuum. Yield 3.59 g
3
(82%). 1H NMR (300 MHz, THF-d8):
d
1.03 t (6H, NCH2CH3, JHH
75.4 MHz): 45.75 (NCH3), 49.54 (NCH3), 68.82 (CH2N), 124.34 (C5),
d
128.92 (C3), 130.98 (C4), 135.44 (C2), 137.22 (C6), 137.26 (C1). 77Se
3
7.1 Hz), 2.56q (4H, NCH2CH3, JHH 7.1 Hz), 3.77s (2H, CH2N), 6.56 t
(CDCl3, 57.26 MHz):
d
ꢀ81.2. MS (EI, 70 eV), m/z (%): 492 (98) [Mþ],
3
3
(1H, C6H4, JHH 7.0 Hz), 6.68 t (1H, C6H4, JHH 7.0 Hz), 7.08dd (1H,
477 (18) [MeMeþ], 278 (23) [2-(Me2NCH2)C6H4SeZnþ], 214 (67) [2-
(Me2NCH2)C6H4Seþ], 134 (100) [2-(Me2NCH2)C6Hþ4 ]. ESIþ m/z (%):
770 (87) [{2-(Me2NCH2)C6H4Se}3Znþ2 ], 515 (100) [MþNa]þ, 428 (67)
[{2-(Me2NCH2)C6H4Se}þ2 ].
C6H4, 3JHH 7.5, 4JHH 1.5 Hz), 7.70dd (1H, C6H4, 3JHH 7.5, 4JHH ¼ 1.5 Hz).
13C (THF-d8, 75.4 MHz):
d 12.03 (NCH2CH3), 47.60 (NCH2CH3), 61.47
(CH2N), 120.52 (C5), 125.21 (C4), 128.68 (C3), 139.33 (C6), 142.28 (C2),
144.74 (C1).
4.4.1. [2-(Me2NCH2)C6H4Se]2Cd (4)
4.4. Synthesis of [2-(Me2NCH2)C6H4Se]2Zn (3)
It was similarly prepared from elemental selenium (0.669 g,
8.47 mmol), [2-(Me2NCH2)C6H4]Li (1.195 g, 8.47 mmol) and CdCl2
(0.776 g, 4.23 mmol). Yield 1.581 g (69.4%). M.p.182 ꢁC. Anal. Found:
Elemental selenium (0.384 g, 4.86 mmol) was added to a solu-
tion of [2-(Me2NCH2)C6H4]Li (0.686 g, 4.86 mmol) in 30 mL

A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
2491
C 39.82, H 4.52, N 5.32%. Calc. for C18H24N2Se2Cd (M ¼ 538.73): C
40.13, H 4.49, N 5.20%. 1H NMR (CDCl3, 300 MHz, 298 K):
1.99s,br
(12H, NCH3), 3.58s,br (4H, CH2N), 6.99 m (6H, C6H4, H3e5), 7.85d (2H,
C6H4, H6, 3JHH 7.2 Hz). 1H NMR (CDCl3, 300 MHz, 213 K):
1.25s (6H,
d
ꢀ94.97. ESIþ m/z (%): 948 (84) [{2-(Et2NCH2)C6H4Se}3Cdþ2 ], 597
d
(48) [M]þ, 485 (100) [{2-(Et2NCH2)C6H4Se}þ2 ].
d
4.7. X-ray structure determination
NCH3), 2.56s (6H, NCH3), AB spin system with dA 2.88 and dB 4.22
(4H, CH2N, 2JHH 11.4 Hz), 6.92d (2H, C6H4, H4, 3JHH 6.8 Hz), 7.00 t (2H,
Block crystals of [2-(Et2NCH2)C6H4]2Se2 (1), [2-(Me2NCH2)
C6H4Se]2Zn (3) and [2-(Me2NCH2)C6H4Se]2Cd (4) were attached
with Paratone N oil on cryoloops. The data were collected at room
3
3
C6H4, H5, JHH 7.1 Hz), 7.08 t (2H, C6H4, H3, JHH 7.3 Hz), 7.84d (2H,
C6H4, H6, 3JHH 7.2 Hz). 13C (CDCl3, 75.4 MHz):
46.64 (NCH3), 67.51
d
(CH2N), 124.70 (C5), 128.62 (C3), 131.66 (C4), 133.84 (C2), 137.88
temperature on a Bruker SMART APEX CCD diffractometer using
(C6,C1). 77Se (CDCl3, 57.26 MHz):
d
ꢀ111.5. 113Cd (CDCl3, 111 MHz):
ꢀ
graphite-monochromated Mo-K
details of the crystal structure determination and refinement are
given in Table 2.
a
radiation (
l
¼ 0.71073 A). The
d
ꢀ196.2. MS (EI, 70 eV), m/z (%): 540 (23) [Mþ], 214 (100) [2-
(Me2NCH2)C6H4Seþ], 134 (38) [2-(Me2NCH2)C6Hþ4 ]. ESIþ m/z (%):
866 (43) [{2-(Me2NCH2)C6H4Se}3Cdþ2 ], 541 (38) [MþH]þ, 428 (100)
[{2-(Me2NCH2)C6H4Se}þ2 ].
The structures were refined with anisotropic thermal parame-
ters. The hydrogen atoms were refined with a riding model and
a mutual isotropic thermal parameter. For structure solving and
refinement the software package SHELX-97 was used [41]. The
drawings were created with the Diamond program [42].
4.5. Synthesis of [2-(Et2NCH2)C6H4Se]2Zn (5)
To a mixture of [2-(Et2NCH2)C6H4]SeNa (0.4 g, 1.51 mmol) and
ZnCl2 (0.102 g, 0.75 mmol) 15 mL of anhydrous THF was added and
the reaction mixture was stirred for 24 h at 55 ꢁC, under argon.
The solvent was removed in vacuum and the obtained solid was
treated with 30 mL toluene. NaCl was filtered off and from the
clear solution the solvent was removed under reduced pressure.
The brown solid residue was washed with 3 ꢂ 20 mL warm hexane
(60 ꢁC) to give the title compound as a white solid. Yield: 0.25 g
(57.3%). M.p. 144e145 ꢁC. Anal. Found: C 47.82.4, H 5.71, N 5.32%.
Calc. for C22H32N2Se2Zn (M ¼ 547.81): C 48.24, H 5.89, N 5.11%. 1H
Acknowledgements
Financial support from National University Research Council
and Ministry of Education and Research of Romania (Research
Projects CEx 11-55/2006 and PNII-ID 2404/2008) is greatly appre-
ciated. We warmly acknowledge Prof. Kieran C. Molloy for helpful
discussions and assistance in 77Se and 113Cd NMR experiments.
Appendix A. Supplementary data
NMR (500 MHz, CDCl3, 298 K): d 0.99s,br (12H, NCH2CH3), 2.81s,br
(8H, NCH2CH3), 3.89s,br (4H, CH2N), 6.99 m (4H, C6H4, H4,5),
CCDC 753670, 753676 and 753671 contain the supplementary
crystallographic data for compounds 1, 3 and 4. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via http://www.ccdc.cam.ac.uk/data_request/cif. The
supplementary material also contains figures representing the
supramolecular associations in the crystals of compounds 3 and 4.
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.jorganchem.2010.07.036.
7.06 m (2H, C6H4, H3), 7.67 m (2H, C6H4, H6). 1H NMR (300 MHz,
3
CD2Cl2, 298 K):
d
0.92 t (12H, NCH2CH3, JHH 7.1 Hz), 2.74q (8H,
NCH2CH3, 3JHH 7.2 Hz), 3.81s,br (4H, CH2N), 6.94 m (4H, C6H4, H4,5),
7.02 m (2H, C6H4, H3), 7.67 m (2H, C6H4, H6). 1H NMR (300 MHz,
CD2Cl2, 238 K): 0.55e1.66 (12H, NCH2CH3), 2.06e3.04 (8H,
NCH2CH3), AB spin system with dA 3.56 and dB 4.18 (4H, CH2N),
7.12 m (6H, C6H4, H3e5), 7.63 m (2H, C6H4, H6). 13C (CDCl3,
75.4 MHz):
d 9.06s,br (NCH2CH3), 46.60s,br (NCH2CH3), 62.99s,br
(CH2N), 124.01 (C5), 128.53 (C4), 131.19 (C3), 135.92 (C6), 136.85
References
(C2), 137.83 (C1). 77Se (CDCl3, 57.26 MHz):
d
ꢀ59.02. ESIþ m/z (%):
854 (58) [{2-(Et2NCH2)C6H4Se}3Znþ2 ], 549 (27) [MþH]þ, 485 (100)
[1] G. Mugesh, H.B. Singh, Chem. Soc. Rev. 29 (2000) 347.
[2] G. Mugesh, H.B. Singh, Acc. Chem. Res. 35 (2002) 226.
[3] K. Kandasamy, S. Kumar, H.B. Singh, R.J. Butcher, K.T. Holman, Eur. J. Inorg.
Chem. (2004) 1014.
[{2-(Et2NCH2)C6H4Se}þ2 ]
[4] S. Kumar, K. Kandasamy, H.B. Singh, G. Wolmershauser, R.J. Butcher, Organ-
ometallics 23 (2004) 4199.
4.6. Synthesis of [2-(Et2NCH2)C6H4Se]2Cd (6)
[5] T.M. Klapötke, B. Krumm, K. Polborn, J. Am. Chem. Soc. 126 (2004) 710.
[6] N. Sudha, H.B. Singh, Coord. Chem. Rev. 135e136 (1994) 469.
[7] Y. You, K. Ahsan, M.R. Detty, J. Am. Chem. Soc. 125 (2003) 4918.
[8] A. Panda, G. Mugesh, H.B. Singh, R.J. Butcher, Organometallics 18 (1999) 1986.
[9] T. Wirth, Angew. Chem., Int. Ed. 39 (2000) 3740.
[10] T. Wirth (Ed.), Organoselenium Chemistry: Modern Developments in Organic
Synthesis, Topics in Current Chemistry, vol. 208, Springer, Berlin, 2000.
[11] K. Fujita, K. Murata, M. Iwaoka, S. Tomoda, Tetrahedron 53 (1997) 2029.
[12] C. Santi, T. Wirth, Tetrahedron: Asymmetry 10 (1999) 1019.
[13] K. Hiroi, Y. Suzuki, I. Abe, Tetrahedron: Asymmetry 10 (1999) 1173.
[14] M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini, L. Bagnoli,
A. Temperini, Tetrahedron: Asymmetry 11 (2000) 4645.
[15] M. Uchiyama, S. Satoh, A. Ohta, Tetrahedron Lett. 42 (2001) 1559.
[16] M. Uchiyama, M. Hirai, M. Nagata, R. Katoh, R. Ogawa, A. Ohta, Tetrahedron
Lett. 42 (2001) 4653.
[17] M. Tiecco, L. Testaferri, C. Santi, C. Tomassini, F. Marini, L. Bagnoli,
A. Temperini, Angew. Chem., Int. Ed. 42 (2003) 3131.
To a solution of [2-(Et2NCH2)C6H4]SeLi (0.55 g, 2.22 mmol) in
15 mL anhydrous THF was added CdCl2 (0.203 g, 1.11 mmol) and the
reaction mixture was stirred for 24 h at room temperature. The
solvent was removed in vacuum and the resulting solid was treated
with 30 mL toluene. LiCl was filtered off and from the clear solution
the solvent was removed under reduced pressure. The obtained
glue was washed with 3 ꢂ10 mL hexane to give the title compound
as a yellowish solid. Yield: 0.45 g (68.3%). M.p. 127e128 ꢁC. Anal.
Found:
C 44.84, H 5.52, 4.82%. Calc. for C22H32N2Se2Cd
(M ¼ 594.84): C 44.42, H 5.42, N 4.71%. 1H NMR (300 MHz, CDCl3,
298 K): d 0.63s,br (12H, NCH2CH3), 2.61s,br (8H, NCH2CH3), 3.82s,br
(4H, CH2N), 6.97e7.02 m (6H, C6H4, H3e5), 7.77d (2H, C6H4, H6, 3JHH
7.6 Hz). 1H NMR (300 MHz, CD2Cl2, 298 K): 0.77s,br (NCH2CH3),
2.53s,br (8H, NCH2CH3), 3.75s,br (4H, CH2N), 6.93 m (6H, C6H4,
H3e5), 7.66 m (2H, C6H4, H6). 1H NMR (300 MHz, CD2Cl2, 223 K):
[18] G. Mugesh, W.-W. du Mont, H. Sies, Chem. Rev. 101 (2001) 2125 and refer-
ences therein.
[19] Y. Cheng, T.J. Emge, J.G. Brennan, Inorg. Chem. 35 (1996) 342.
[20] Y. Cheng, T.J. Emge, J.G. Brennan, Inorg. Chem. 35 (1996) 7339.
[21] Y. Cheng, T.J. Emge, J.G. Brennan, Inorg. Chem. 33 (1994) 3711.
[22] R. Kaur, H.B. Singh, R.P. Patel, S.K. Kulshreshta, J. Chem. Soc., Dalton Trans.
(1996) 461 and references cited therein.
[23] G. Mugesh, H.B. Singh, R.P. Patel, R.J. Butcher, Inorg. Chem. 37 (1998) 2663.
[24] M. Bochmann, G.C. Bwembya, A.K. Powell, X. Song, Polyhedron 23e24 (1995)
3495.
d
ꢀ0.16s,br (6H, NCH2CH3), 1.08s,br (6H, NCH2CH3), 1.98s,br (4H,
NCH2CH3), 2.92s,br (4H, NCH2CH3), AB spin system with dA 3.21 and
dB 4.15 (4H, CH2N, 2JHH 9.5 Hz), 6.88 m (6H, C6H4, H3e5), 7.60 m (2H,
C6H4, H6). 13C (CDCl3, 75.4 MHz, 298 K):
d 9.65 (NCH2CH3), 47.74
(NCH2CH3), 61.41 (CH2N), 124.53 (C5), 128.55 (C4), 132.04 (C3),
134.89 (C6), 137.10 (C2), 137.81 (C1). 77Se (CDCl3, 57.26 MHz):
[25] M. Bochmann, K.J. Webb, J. Chem. Soc., Dalton Trans. (1991) 2325.

2492
A. Pöllnitz et al. / Journal of Organometallic Chemistry 695 (2010) 2486e2492
[26] M. Bochmann, K.J. Webb, M.B. Hursthouse, M. Mazid, J. Chem. Soc., Dalton
Trans. (1991) 2317.
[27] M. Bochmann, A.P. Coleman, K.J. Webb, M.B. Hursthouse, M. Mazid, Angew.
Chem, Int. Ed. Engl 30 (1991) 973.
[34] M. Kulcsar, A. Silvestru, C. Silvestru, J.E. Drake, C.L.B. Macdonald,
M.E. Hursthouse, M.E. Light, J. Organomet. Chem. 690 (2005) 3217.
[35] A. Beleaga, M. Kulcsar, C. Deleanu, A. Nicolescu, C. Silvestru, A. Silvestru,
J. Organomet. Chem. 694 (2009) 1308.
[28] M. Bochmann, K.J. Webb, M. Harman, M.B. Hursthouse, Angew. Chem, Int. Ed.
Engl. 29 (1990) 638.
[36] M. Kulcsar, A. Beleaga, C. Silvestru, A. Nicolescu, C. Deleanu, C. Todasca,
A. Silvestru, J. Chem. Soc., Dalton Trans. (2007) 2187.
[29] G. Mugesh, H.B. Singh, R.J. Butcher, J. Organomet. Chem. 577 (1999) 243.
[30] J.G. Brennan, T. Siegrist, P.J. Carroll, S.M. Stuczynski, P. Reynders, L.E. Brus,
M.L. Steigerwald, Chem. Mater. 2 (1990) 403.
[31] J.G. Brennan, T. Siegrist, P.J. Carroll, S.M. Stuczynski, L.E. Brus, M.L. Steigerwald,
J. Am. Chem. Soc. 111 (1989) 4141.
[32] M. Bochmann, G.C. Bwembya, R. Grinter, A.K. Powell, K.J. Webb,
M.B. Hursthouse, K.-M. Abdul-Malik, M.A. Majid, Inorg. Chem. 33 (1994) 2290.
[33] P.J. Bonasia, J. Arnold, J. Organomet. Chem. 449 (1993) 147.
[37] R. Kaur, H.B. Singh, R.P. Patel, J. Chem. Soc., Dalton Trans. (1996) 2719.
[38] J. Emsley, Die Elemente. Walter de Gruyter, Berlin, 1994.
[39] G. Mugesh, A. Panda, H.B. Singh, N.S. Punekar, R.J. Butcher, J. Am. Chem. Soc.
123 (2001) 839.
[40] P.N. Jayaram, G. Roy, G. Mugesh, J. Chem. Sci. 120 (2008) 143.
[41] G.M. Sheldrick, Acta Crystallogr. Sect. A 64 (2008) 112.
[42] DIAMONDdVisual Crystal Structure Information System, CRYSTAL IMPACT,
Bonn, Germany, 2001.